1. Field of the Invention
The invention relates generally to plasma generators, and more particularly to matching networks for RF driven plasma generators which may be used as ion or electron sources.
2. Description of the Prior Art
Multicusp plasma generators are used in ion (or electron) sources. While the plasma may be generated by a dc filament discharge, an inductively driven plasma generator using an RF antenna in the plasma production chamber is cleaner.
A matching network is needed for operating a plasma generator with an RF power supply. This is to eliminate the reflected power at the power supply/antenna interface so that the maximum power output from the supply is delivered into the plasma generator. The matching network is connected between the external RF power supply and the RF antenna inside the plasma production chamber.
U.S. Pat. No. 5,587,226 shows a plasma ion source with a general representation of a matching network coupling the RF supply to the RF antenna. No specific circuit design and structure are shown.
Matching networks are normally large in size and cannot be incorporated into a compact Focused Ion Beam (FIB) system such as described in U.S. Pat. No. 5,945,677. Thus a design is needed which meets the size requirement for a compact FIB tool.